Archive for the ‘ L1-Anat Thorax ’ Category

L1-Thoracic Wall

OBJECTIVE

1) Thoracic Cage

    Surface Marking

2) Intercostal Spaces

  • Intercostal Muscles
  • Intercostal Vessels & Nerves
  • 3) Diaphragm

    4) Pleura

    5) Surface Anatomy

    [1] THORACIC CAGE

    • the ribs and intercostal spaces on each side
    • the sternum and costal cartilage in front
    • the vertebral column behind
    • above; the THORACIC INLET communicates with root of the neck
    • below; the THORACIC OUTLET separated from the abdominal cavity by diaphragm

    TYPICAL RIBS

    • curved
    • Posterior End
    1. Head
    2. Tubercle
    • Anterior End
    • Costal Groove
    • articulate with 2 vertebrae
    • the synovial joint permits up and down rib movements

    SURFACE MARKING

    • sternum (3 parts)
    • jugular notch
    • sternal angle
    • clavicle
    • costal margin
    • infrasternal angle
    • midclavicular line
    • midaxillary line

    [2] INTERCOSTAL SPACE

    DEFINITIONIt is the space between 2 ribs

    NUMBER11

    CONTENTS:

    • Intercostal Muscles
    • Intercostal Vessels
    • Intercostal Nerves
    • Lymphatics

    →INTERCOSTAL MUSCLES

    1) THE EXTERNAL INTERCOSTAL MUSCLE

    • its fiber pass forwards
    • extend from tubercle of ribs to costocartilage junctions
    • continues as EXTERNAL INTERCOSTAL MEMBRANE
    • elevate the ribs during inspiration

    ORIGIN:

    -Lower border of rib above

    INSERTION:

    -Upper border of rib below

    DIRECTION OF FIBERS:

    -Downward and Forward

    EXTENT:

    -From the tubercle of rib (behind) to the costochondral junction (in front) where it continues as a membrane (ANTERIOR @ EXTERNAL INTERCOSTAL MEMBRANE)

    NERVE SUPPLY:

    -Intercostal Nerves

    ACTION:

    Elevation of ribs during inspiration

    2) THE INTERNAL INTERCOSTAL MUSCLE

    • its fibers pass backwards
    • extends from edge of sternum to angle of the rib
    • continues as INTERNAL INTERCOSTAL MEMBRANE
    • depress ribs in expiration

    ORIGIN:

    -Costal groove of rib above

    INSERTION:

    -Upper border of tib below

    DIRECTION OF FIBERS:

    -Downward and Backward

    EXTENT:

    -From lateral margin of sternum (anteriorly) to the angle of rib (posteriorly) where it continues as a membrane (POSTERIOR @ INTERNAL INTERCOSTAL MEMBRANE)

    NERVE SUPPLY:

    -Intercostal Nerve

    ACTION:

    -Elevation of ribs during expiration

    3) TRANSVERSUS THORACIC MUSCLE

    • is separated from intenal intercostal muscle by the NEUROVASCULAR BUNDLE
    • the fibers of this sheet cross more than one space
    1. Subcostalis
    2. Intercostalis Intimi (Innermost Intercostal)
    3. Sternocostalis

    1- STERNOCOSTALIS MUSCLE

    ORIGIN:

    -Lower 1/3 posterior surface of body of sternum & xiphoid process

    INSERTION:

    -Costal cartilages from 2nd to 6th

    DIRECTION OF FIBERS:

    -Upward and laterally

    NERVE SUPPLY:

    -Intercostal Nerve

    ACTION:

    -Support the sternocostal joint

    2- INTERCOSTALIS INTIMI MUSCLE

    ORIGIN:

    -Lower border of rib above

    INSERTION:

    -Upper border of rib below

    DIRECTION OF FIBERS:

    -Downwards and Backward (as inner intercostal ms)

    -Along the mid 2/4 of intercostal space

    NERVE SUPPLY:

    -Intercostal Nerves

    ACTION:

    -Elevation of ribs during inspiration

    3- SUBSCOSTALIS MUSCLE

    ORIGIN:

    -Slips from the inner surface of rib at its angle

    INSERTION:

    -The 2nd or 3rd rib below

    DIRECTION OF FIBERS:

    -Downward and Medially

    NERVE SUPPLY:

    -Intercostal nerve

    ACTION:

    -Depress the ribs during expiration

    →INTERCOSTAL VESSELS AND NERVES

    • VAN (vein , artery , nerve)
    • lie in subcostal groove
    • between Internal Intercostal and Innermost Intercostal Muscle

    ARTERIES

    1) ANTERIOR INTERCOSTAL ARTERIES

    NO:

    -TWO  in each space (9 spaces) = 18

    BEGINNING:

    -upper 6 from INTERNAL THORACIC ARTERY

    -lower 3 from MUSCULOPHRENIC ARTERY (branch of Internal Thoracic Artery)

    TERMINATION:

    -by anastomosing with POSTERIOR INTERCOSTAL ARTERIES & their collateral branches

    COURSE:

    -pass laterally in the intercostal space

    (1) – Internal Thoracic @ Mammary Artery

    (2) – Supreme Thoracic Artery(branch of axillary a.)

    (3) – Lateral Thoracic Artery

    (4) – Intercostal Artery

    2) POSTERIOR INTERCOSTAL ARTERIES

    NO:

    -one in each space (11 spaces) = 11

    BEGINNING:

    -upper 2 from sup intercostal artery branch of costocervical trunk of 2ND part  SUBCLAVIAN ARTERY

    -lower 9 from branches of descending THORACIC AORTA

    TERMINATION:

    -ends near the costochondral junction by anastomosing with CORRESPONDING ANTERIOR INTERCOSTAL ARTERY

    BRANCHES:

    1)DORSAL B.

    -arise at neck of rib

    -supplies muscle and skin of back and the spinal cord & its meninges

    2)COLLATERAL BRANCH

    -arises near the angle of rib

    -runs along the upper border of rib below

    -terminates by anastomosing w/ ANT INTERCOSTAL A.

    3)LATERAL CUTANEOUS B.

    -arises near angle of rib

    -accompanies the lateral cutaneous branch of intercostal nerve

    4)MAMMARY B.

    -arises from 2nd , 3rd , 4th POST INTERCOSTAL A.

    -supplies the lateral parts of the mammary gland(breast)

    5)MUSCULAR B.

    -to the surrounding muscles

    6)RIGHT BRONCHIAL ARTERY

    -from right third POST INTERCOSTAL A.

    3) INTERNAL THORACIC (MAMMARY ARTERY)

    ORIGIN:

    -first part of SUBCLAVIAN A.

    TERMINATION:

    -opposite 6th intercostal space by dividing into

    1. SUPERIOR EPIGASTRIC ARTERY
    2. MUSCULOPHRENIC ARTERY

    COURSE & RELATIONS:

    -descend downward and medially

    -behind clavicle and 1st costal cartilage

    -descend vertically downward to termination @ 6th i. space

    BRANCHES:

    1)PERICARDIOPHRENIC A.

    -runs w/ phrenic nerve

    -supplies pericardium, pleura, diaphragm

    2)ANTERIOR INTERCOSTAL A.

    -two for each space(6 spaces)

    3)PERFORATING A.

    -accompany anterior cutaneous nerve and the perforating branches of 2nd, 3rd, and 4th spaces supplying mamary gland

    4)MUSCULOPHRENIC A

    5)SUPERIOR EPIGASTRIC A.

    (1)-Internal Thoracic or Mammary Artery

    VEIN

    1) INTERNAL THORACIC VEIN

    BEGINNING:

    -behind 3rd costal cartilage by union of vena commitants of INTERNAL MAMMARY ARTERY (which is the result of union of vena commitants of SUP EPIGASTRIC & MUSCULOPHRENIC A.)

    TERMINATION:

    -in corresponding brachiocephalic vein

    TRIBUTARIES:

    -corresponding to the branches of INTERNAL THORACIC A.

    2) ANTERIOR INTERCOSTAL V.

    -drain into INTERNAL THORACIC V.

    3) POSTERIOR INTERCOSTAL V.

    -drain into the AZYGOS system of veins

    4) LEFT SUPERIOR INTERCOSTAL V.

    -drain into LEFT BRACHIOCEPHALIC V

    NERVE

    INTERCOSTAL NERVES

    DEFINITION:

    -Ventral rami of thoracic spinal nerves in corresponding intercostal space.

    -The last thoracic nerve (12th) called SUBCOSTAL NERVE

    NO:

    -11 intercostal nerves pass in the corresponding intercostal spaces

    TYPES:

    1) TYPICAL INTERCOSTAL NERVE

    -from 3rd to 6th (only at chest wall only)

    2) ATYPICAL INTERCOSTAL NERVE

    -upper 2 and last 5 (outside chest wall)

    1) TYPICAL INTERCOSTAL NERVES

    NO:

    -from 3rd to 6th i-spaces

    BEGINNING:

    -exit from corresponding intervertebral foramen from 3rd to 6th intercostal nerves

    TERMINATION:

    -between Internal I-C Ms and Ant I-C Membrane

    -as Anterior Cutaneous Nerve

    COURSE & RELATIONS:

    1) exits from the corresponding intervertebral foramen

    2) pass btwn parietal pleura and post intercostal membrane

    3) at angle of ribs, it split the internal intercostal muscle into internal intercostal muscle (outer layer) and innermost intercostal muscle (inner layer)

    4) enter costal groove where it lies below the posterior intercostal vessels (V.A.N)

    5) at costochondral junctions,it comes out from internal intercostal muscle and runs btwn it and pleura

    6) about 1 cm lateral to the sternum, the nerve pierce the internal intercostal muscle and anterior intercostal membrane, to terminate as ANTERIOR CUTANEOUS NERVE

    BRANCHES:

    1)GANGLIONIC B.

    -it give a white myelinated (preganglionic) ramus communicant to the sympathetic trunk and receive a gray unmyelinated (postganglionic) ramus communicant from the correponding ganglion of sympathetic trunk

    2)MUSCULAR B.

    -to supply intercostal muscles

    3)COLLATERAL B.

    -runs along the upper border of rib below

    4)LATERAL CUTANEOUS B.

    -arises close to the angle of rib and pierce the internal and external intercostal muscles

    -supply skin at side of chest

    5)ANTERIOR CUTANEOUS B.

    -is the termination of the intercostal nerve

    -supply the skin on front of chest

    2) ATYPICAL INTERCOSTAL NERVES

    BRANCHES

    1)THE 1ST INTERCOSTAL NERVE

    -it is atypical because

    only small part of it forms the 1st intercostal nerve

    but the larger part ascend in front of neck of 1 st rib to share in formation of brachial plexus of upper limb

    2)THE 2ND INTERCOSTAL NERVE

    -it is atypical because

    it supplies the skin of axilla and the arm by its lateral cutaneous branch, which enters the arm as intercostobrachial nerve

    3)THE LOWER 5 INTERCOSTAL NERVES

    -they are atypical because

    their complete courses are in the abdomen